Yes, as I previously stated I am using GCC 4.9.0 Mingw-w64. Both the ml64 dependency and the warnings are annoying. Never had such issues with regular C object files built with MSVC though. ________________________________ From: Boost-users [boost-users-bounces@lists.boost.org] on behalf of Oliver Kowalke [oliver.kowalke@gmail.com] Sent: Saturday, July 05, 2014 5:46 PM To: boost-users Subject: Re: [Boost-users] Limitations of BOOST_COROUTINES_V2 (pass by reference) 2014-07-05 13:43 GMT+02:00 Mueller-Roemer, Johannes Sebastian <Johannes.Sebastian.Mueller-Roemer@igd.fraunhofer.de<mailto:Johannes.Sebastian.Mueller-Roemer@igd.fraunhofer.de>>: I just build the current git version and it appears to work now. The "Warning: corrupt .drectve at end of def file" are still produced though. you are using mingw? mingw has some problems with objects in MS PE binary format - other compilers (like gcc/clang on UNIX or msvc on WIndows) have no problems.